Abstract
The morphology of the adult worm and the egg of Toxascaris leonina was studied comparatively with parasites obtained from dogs, cats, tigers, and cheetahs. Several considerable differences were observed. The disparity between the canine and feline strains was the largest, and the values determined in the tiger and cheetah strains were found in between. Noticeable points are summarized as follows. 1. The body length and width in the canine strain were the greatest. There were statistically significant differences (at a 1% level) in these points between this strain and the other three Felidae strains. 2. The esophagus/body length ratio was the lowest in the canine strain. There was a significant difference in this ratio between the canine strain and any of the other three Felidae strains, except the tiger strain in the case of females. 3. The vulvae were situated more backward in the other three Felidae strains than in the canine strain. 4. The width of the cervical alae was greater in the feline strain than in the canine strain. There was a distinct difference in the width/length ratio of the cervical alae between the two strains. 5. The egg of the canine strain was the largest in size, especially in length, and that of the tiger strain the smallest of those of the four strains.
